1. Field of the Invention
The present invention relates to multipoint injection, and more particularly to multipoint fuel injection such as in gas turbine engines.
2. Description of Related Art
NASA's “Environmentally Responsible Aircraft” (ERA) N+2 advanced, low NOx combustor technologies program is looking at combustion technologies suitable for the 2020 time frame. The objective of this program is to develop fuel-air mixing concepts and associated fuel control valves. The low emissions combustor concept must be capable of meeting or exceeding the N+2 LTO NOx goal of 75% reduction from the ICAO standard adopted by CAEP 6 at engine pressure ratios of at least 55.
In the early 2000's, the ability of a multipoint lean direct injection (LDI) concept was demonstrated to achieve very low NOx emissions index (EI) levels as tested at the NASA high pressure test facilities. The program was successful in demonstrating the ability of the multipoint concept to deal with NOx at high power conditions but was not optimized to perform equally as well at low power conditions such as start, ground idle, and flight idle conditions.
Conventional methods and systems have generally been considered satisfactory for their intended purpose. However, there is still an need in the art for a multipoint fuel injection arrangement that allows for improved performance at high and low power operation while significantly reducing NOx emissions. There also remains a need in the art for such a multipoint fuel injection arrangement that is easy to make and use. The present invention provides a solution for these problems.